The present invention relates to a non-rectangular thermo module for use in cooling a semiconductor wafer and a cooling device formed using the same.
In a cooling device for cooling a semiconductor wafer, generally, as show in FIGS. 12 and 13, a plurality of thermo modules 3 are disposed between a circular cooling plate 1 for cooling a wafer W and a heat radiating blocks 2 for radiating heat to the outside and fastened together with a plurality of screws 4. A plurality of lifter pins 5 supporting the wafer W pass through the heat radiating blocks 2 and the cooling plate 1, such that they are protruded from a top face of the cooling plate 1 movably in the vertical direction. Reference numeral 6 denotes a refrigerant flow path.
In this kind of a conventional cooling device, as shown in FIG. 13, the aforementioned thermo modules 3 are cubic or rectangular and the thermo modules 3 are disposed in a circular plane of a cooling plate 1. Thus, the thermo modules 3 are difficult to dispose without a gap, so that much dead space exists. As a result, a temperature gradient between a place where thermo module 3 exists and a place where no thermo module exists cannot be avoided, thereby making it difficult to cool the wafer uniformly and inducing a poor cooling efficiency. Further, the thermo module 3 cannot be installed at a tightening position of the screw and an installation position of a lifter pin 5 so as to avoid them, so that a portion where the thermo modules are not installed occupies a large area of the cooling plate. The aforementioned temperature gradient appears more remarkably if the cooling plate 1 is thinned to reduce the weight, heat capacity thereof and the like.
Although the cooling plate 1 is desired to be thinned to reduce its heat capacity for reduction of cooling time, it is more likely to be deformed when it is tightened with the screw 4 accompanied by such thinning, so that the flatness drops.
Unless each thermo module 3 is disposed accurately at a predetermined position of the cooling plate 1 when the cooling plate 1 is combined with the thermo module 3, an unbalanced temperature gradient occurs. For the reason, concave portions for fixing the thermo modules are provided in the cooling plate or the thermo modules are fixed with a spacer. Even if such countermeasure is taken, the thermo module may ride over the surrounding of the concave portion or spacer, so that an installation failure may occur. Therefore, it is desirable that the thermo modules are disposed accurately without causing the installation failure.
A technical object of the present invention is to provide a thermo module which can be densely installed in a circular plane of a disc type cooling plate in a cooling device and be effective for improvement of its cooling capacity and reduction of a temperature gradient.
Another technical object of the present invention is to provide a cooling device intended to improve the cooling capacity and reduce the temperature gradient using the aforementioned thermo module.
To achieve the above-described object, according to the present invention, there is provided a non-rectangular thermo module formed by disposing a plurality of Peltier devices between a pair of opposing heat radiating plates, wherein the heat radiating plate has a circular or straight outer peripheral contour portion and inner peripheral contour position and right/left side contour portions connecting the outer peripheral contour portion and the inner peripheral contour portion and the outer peripheral contour portion is formed so as to be longer than the inner peripheral contour portion while the right/left side edge contour portions contain first straight lines which are not parallel and inclined toward the inner peripheral contour portion such that they narrow gradually, the first straight lines being provided at least in part of the right/left side edge contour portions.
Although the right/left side edge contour portions of the heat radiating plate in the aforementioned thermo module may be formed entirely of the first straight lines, its portion which is on the side of the inner peripheral contour portion may be formed of the first straight line while its portion which is on the side of the outer peripheral contour portion may be formed of second straight lines which are parallel to each other.
Further, a plurality of Peltier devices may be disposed such that the installation density thereof has a gradient from the inner peripheral contour portion of the heat radiating plate toward the outer peripheral contour portion.
Further, the thermo module may include a through hole which passes through the pair of the heat radiating plates.
According to the present invention, there is provided a wafer cooling device wherein a plurality of the thermo modules having the above-described structure are disposed coaxially between a circular cooling plate for cooling the wafer and a heat radiating block for radiating heat to the outside such that the first straight lines of adjacent thermo modules are parallel and adjacent to each other.
In the wafer cooling device, thermo modules located on an inner disc and thermo modules located on an outer disc each may have a different shape and dimensions from each other.
Further, in the present invention, preferably, the cooling plate, the thermo modules and the heat radiating block are fastened to each other with screws passing through each of the thermo modules at an installation position of at least part of the thermo modules.
Preferably, adjacent thermo modules disposed in a circular shape are connected to each other with conductive wire successively so that the thermo modules are maintained in a necessary installation pattern by the conductive wire.